Slitting crowned strip and mechanism therefor



June 16, 1942. c. J. GIBBONS 2,286,675

SLI TTING CROWNED STRIP AND MECHANISM THEREFOR Filed May 51, 1941 INVENTOR G/Bsa/vs.

ATTORNEYS.

CHARL E6 11 Patented June 16, 1942 SLITTING CROWNED s'rnrr m MECHANISM THEREFOR Charles J. Gibbons, Middletown, Ohio, assignor to The American Rolling Mill Company, Middletown, Ohio, a corporation of Ohio Application May 31, 1941, Serial No. 396,029

8 Claims. (Cl. 164-65) My invention relates to the slitting of wide strip metal to form coils of strip of narrower width, and in particular to the slitting of crowned strip.

Continuous, iron or mildv steel strip is today made in tremendous quantities in wide widths on the modern continuous mill. The material is made in accordance with the teachings of the Tytus Re. Patent No. 16,884, and is characterized by a slight crown, i. e., it is thicker in the center than at the edges, it is frequently necessary to slit such wide widths into two or more strips of narrower width for convenience of handling and customers applications.

The cutting of two or more strips from wider,

, crowned strip, with the production of tight, even coils suitable for box annealing or shipment, has not hitherto been possible. ,The material has been slitted; but it has been necessary to wind up the narrower coils on reels located some thirty or forty feet from the slitting point. Also, in order to prevent excessive "crowding of strip which ruined the edges. It has been necessary to use low slitting speeds and great care. In spite of all precautions, this procedure has not produced coils suitable for shipment or box annealing. A rewinding of the coils has been found necessary before annealing; and if the product was a finished product intended for shipment, a temper pass through a mill, as well as arecoiling was found to be required to make a salable coil with good edges. These treatments increased the cost of production of the strip and even then did not give the best quality.

-The primary objects of my invention are the elimination of the difficulties pointed out above; the provision of a slitting and coiling method which will give, with one operation, tight, even coils of crowned stock having a good fiat surface across the strip, particularly at the edge; the provision of a mechanism for the purpose which is close-coupled and occupies a minimum of floor space; the formation of a plurality of tight and even coils of slitted stockon the same mandrel, or on coaxial mandrels; and the elimination of recoilings and after-treatments.

These and other objectsof my invention which will be set forth hereinafter or will be apparent to one skilled in the art upon reading these specifications, I accomplish by that certain procedure and in that apparatus of which I shall now describe an exemplary embodiment. Reference is made to the drawing wherein I have shown diagrammatically a form of my apparatus.

When slitting and coiling crowned stock, the

heavier center in the wide strip tends to build up the inside edge of the slit coils. To put this another way, the slight additional thickness of the edge of the slitted material which was nearest the center of the original coil tends to produce coils which have a larger outside diameter on one edge than on the other.

This condition causes the coiling strip to tend to run toward the heavier edge of the slitted material being coiled, i. e., toward the center line of the original coil which is being slit to form the narrower coils. Therefore, if tight coiling is attempted a crowded or upsetinner edge will be produced on the slitted material. This not only is likely to ruin or impair the strip, but makes the production of tight wound, even coils impossible. The coils so produced are not suitable either for annealing or for shipment;

Briefly, in the practice of my invention, when slitting crowned strip material, I make a double cut at the central division line intermediate the edges of the original strip and continuously remove a narrow width of the material along such division line. The narrow width so removed will hereinafter, for convenience, be referred to as the ribbon. The width of the ribbon for any given shearing operation should be calculated on the basis of the crown of the material at the division line and the number of laps on finished coils-in other words the strip length. A given ribbon-width will be required by a given crown and a given number of convolutions in the coils to provide the space necessary to compensate for the tendency of the slitted stock to run to center; and while a greater ribbon width may be employed, holding the ribbon width down as nearly as practicable to the minimum, will minimize waste. However proper provisions and equipment will permit coiling and salvage of ribbon.

This principle is mainly efie'ctive and necessary when a relatively wide, crowned strip is being slit into two narrower coils. However, it may also be found essential in slitting more than two strips from a wide, crowned strip.

The clearance needed between the coils is variable, but may readily be calculated. If, for example, a 26 gauge coil with a one-half point center or crown is being slit centrally into two narrower widths and is being wound onto a twenty inch reel or mandrel to form coils having a four-inch wall thickness, there will be about 200 laps or convolutions in such coils. Two hundred times the half-point crown would be one-tenth of an inch, the amount by which the outer diameter of the slitted coils on the inside edge thereof will exceed the outer diameter on the outside thereof. The term inside refers to the end of the slitted coil nearest the center line of the original coil; and the term outside refers to the end of the slitted coil nearest the outside edge of the original coil. The term slitted coil refers to the coil formed of strip slit from the strip in the original coil. Since the two slitted coils are acting similarly, in this example, and both have the simultaneous tendency to run to center, it is necessary to double the figure of one-tenth of an inch given above. Under these circumstances the ribbon should be approximately two tenths of an inch wide to make possible the unobstructed and tight winding of the slitted coils. If a flange is to be located between the slitted coils, allowance for the thickness of the flange may also be made in the thickness of the ribbon.

I have found that by following the procedure outlined above, and slitting under tension, i. e., with the strip tensioned ahead of and behind the slitting means, I can produce tight, even coils of slitted, crowned strip stock in a close coupled machine, and that the coils so formed are suitable either for box annealing as such or for shipment.

Referring to the drawing, the strip I is shown as being unwound from the original coil 2 on a mandrel 3. A pair of rolls 4 and 5 form parts of the slitting mechanism. They may be provided with mating traction ribs 6; and they will be provided with one or more sets of shear elements for making intermediate cuts in the material. I have shown a knife element 9 and In on the roll 5. This element is a double edged knife or shear member having a width between cutting edges equal to the width of the desired ribbon 8 to be removed frbm the slitted stock. On the top roll or shaft 4 there will be a single knife blade I. This single knife engages both central knives 9 and II] of bottomroll 5. In other words, one male knife (top) engages two female knives (lower) to cut out ribbon from coil. A guide or finger I9 is employed to properly direct the small strip of metal away from slitting knives. It will be understood that as many of the shear knife assemblies are provided as are required by the number of longitudinal intermediate cuts desired. In addition, the outside edges of the original strip may be trimmed or sheared as by additional shear knife assemblies H and I2.

The rolls 4 and 5 may be driven if desired; but this is not necessary since the strip will preferably be pulled through them. The slitted strip may be passed through guide and pinch rolls I3 and I4, and will be coiled up into individual slitted coils I5 and I6 (or more, as desired) on the mandrel H. The slitted coils may be separated by a flange l8.

The mandrel 3 will be suitably braked as at to apply back tension upon the strip, and the mandrel I! will be driven by a motor or other means, not shown, driving the gear 2| to impart forward tension. The strip may, as indicated, be driven by the tension difference.

Modifications may be made in my invention without departing from the spirit of it. Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is: '1. A process of slitting crowned strip which comprises passing the strip under tension from a decoiling point to a recoiling point, intermediatethe said points passing the said strip through a slitting mechanism whereby to divide the strip into divisions for recoiling, and at the slitting point, continuously severing from the strip between said divisions a narrow ribbon of metal the width of which is at least sufiicient to compensate for the tendency of the multiple resulting strip material when recoiled to run toward the inside edge thereof which is thicker by reason of the aforesaid crown, and removing said narrow ribbon from the path of said divisions.

2. A process of slitting crowned metallic strip which comprises decoiling a strip, slitting the strip'into at least two parts longitudinally and recoiling-the slitted strip into a plurality of slitted coils disposedrcoaxially, which slitted coils, by reason of the said crown tend to run toward the thicker edge of the material therein and at the slitting point severing from the original strip continuously, and removing from the path of said parts, a narrow ribbon of metal of a width based on the said tendency, thereby providing tight, even coils with commercially acceptable edges.

3. A process of slitting crowned metallic strip which comprises decoiling a strip, slitting the strip into at least two parts longitudinally and recoiling the slitted strip into a plurality of slitted coils disposed coaxially, which slitted coils, by reason of the said crown tend to run toward the thicker edge of the material therein and at the slitting point severing from the original strip continuously, and removing from the path of said parts, a narrow ribbon of metal of a width based on the said tendency the said width being at least as great as the difference between the thicknesses of the slitted strip at its edges. multiplied by the numberof convolutions to be formed in the coils of slitted material, times two.

4. A method of slitting crowned strip which comprises decoiling crowned strip, slitting it and recoiling it into a plurality of slitted coils, all of said operations being conducted under tension, the coiling and decoiling points being closely spaced, and continuously removing at the line of the central longitudinal slit formed in the strip, a ribbon of metal of a width sufiicient to compensate for the tendency of the slitted coils to run toward each other because of the crown in the original strip.

5. In a slitting mechanism, decoiling means for the original strip and recoiling means for the slitted strip and slitting means intermediate the first mentioned means, said slitting means comprising means for severing the strip longitudinally by making a cut therein intermediate its edges, the central intermediate slitting means comprising means for removing from the original strip, and from the path of the severed parts, a narrow ribbon of metal to compensate for the tendency of the slitted coils to run toward each other.

6. In a slitting mechanism, decoiling means for the original strip and recoiling' means for the slitted strip and slitting means intermediate the first mentioned means, said slitting means comprising means for severing the longitudinal strip by making a cut therein intermediate its edges, such central intermediate slitting means comprising means for removing from the original strip, and from the path of the severed parts, a narrow ribbon of metal to compensate for the tendency of the slitted coils to run toward each other, means for restraining said decoiling means and means for driving said recoiling means such as to subject the strip as it passes from one to the other to substantial tension and such as to wind the slitted coils under tension.

'7. In slitting means, in the order named a decoiler provided with restraining means, a slitting mechanism comprising slitting rolls bearing coacting knives one set at least of which is positioned to sever the strip longitudinally, and recoiling means for a plurality of coaxial coils of the slitted means for driving said recoiling means whereby to subject the strip to tension, a central knife assembly'for producing a longitudinal slit intermediate the edges of the strip comprising means for removing from the strip, and from the path of travel of the severed parts, along the line of said slit, a narrow band of metal.

8. In slitting means, in the order named a decoiler provided with restraining means, a slitting mechanism comprising slitting rolls bearing coacting knives one set at least of which is positioned to sever the strip longitudinally, and recoiling means for a plurality of coaxial coils of the slitted means for driving said recoiling means whereby to subject the strip to tension,- a

central knife assembly for producing a longitudinal slit intermediate the edges of the strip comprising means for removing from the strip, and from the path of travel of the severedparts, along the line of said slit, a narrow band of metal, said slitting means including means for 15 trimming the edges of the strip.

CHARLES J. GIBBONS. 

